The usual eyeglass frame hinge employs a pair of interfitting metal parts pivotally connected together and respectively fixed to the lens frame and to the associated temple piece. The interfitting hinge parts are very small and difficult to handle, are subject to spurious disassembly, and are not readily attachable to associated plastic lens frames and temple pieces, particularly when replacement of the hinge becomes necessary. It would, therefore, be desireable to provide a new and improved eyeglass frame construction wherein the lens frame itself provides better wearing parts of each of the hinge assemblies which connect the temple pieces to the lens frame. It would also be desireable to incorporate in such hinges detent means for holding the temple pieces in the open and closed positions.
Such eyeglasses should also enable adjustment of the pantoscopic and retroscopic angles of the lens in the frame thereby enabling the Doctor to fit faces and optical requirements of various sizes and shapes and to orient bifocal lenses for optimum vision through the lens portions which have the shorter focal length and direct them primarily at the fovea centralis for maximum definition.